Dehumidifier Activation (X And H Terminal Block Pins 11 – N); Compressor Short Cycling Protection (Timeguard); Minimum Compressor Run Time; Water Freeze Protection - Carrier 30AWH004HB Service Manual

Dehumidifier activation (X and H terminal block pins 11 – N)
External dehumidifier source is based on NUI Relative Humidity value, (For this feature is necessary install 33AW-CS1
interface).
Two codes shall be accesses through NUI:
Code 108:
It is for defining availability of external dehumidifier.
1 = Alarm or Defrost
2 = External Dehumidifier activation
Code 107:
- It is Relative Humidity Limit value to activate the heat source.
- If Relative Humidity is higher than Humidity Limit, Output PINS 11-N must be forced ON and display dry mode icon on
NUI.
Protections are activated based on operative Mode.

Compressor Short Cycling Protection (Timeguard)

seconds. During that time F(n) = 0, and a Cool Satisfied or Heat Satisfied message is sent to the Unit depending on the
mode.
last on cycle was shorter than 10 minutes. (The maximum number of cycles for hours is six).
Water Pump remains always ON during Timeguard.

Minimum Compressor Run Time

For reliability purposes this algorithm forces the compressor to run for a minimum amount of time.
This protection is ignored when:
- A/C Power Interruption
- A mode change occurs
- 20 second loss of high voltage communications
- High temperature protection

Water Freeze Protection

When the water starts gets too cold, there is the risk of freezing in the heat exchanger.
Certain actions are taken to prevent freezing.
This protection starts if TR or Tw go down particular values as per conditions below.
TR
-3 ° C
-5 °C
-7 ° C
While in Zone N or H the frequency can't increase.
While in Zone M the frequency is forced to decrease until Fcmin.
SM_30AW.indd 59
Tw
5 ° C
H
4 ° C
2 ° C
Control management
N
M
Compressor OFF
59
5
NUI code 108
and 107
Tw:
Min(Actual
Water
Temperature
Entering,
Actual Water
Temperature
Exiting)
Fr(n):
real frequency
from the Unit
Fcmin:
minimum
compressor
speed allowed
in cooling
TR:
Refrigerant
temperature
30AW
14-03-2011 14:45:06